Field of the Invention
The invention is in the field of optical data transmission engineering and relates to electrooptic coupling arrangements with the aid of which electrooptic component at the arrangement end can be coupled to coupling partners, in particular to optical conductors. These components, which are also termed electrooptic transducers below, can be constructed as a transmitter (for example laser diode) or receiver (for example photodiode). When driven electrically, an electrooptic transducer constructed as a transmitter converts the electric signals into optical signals which are emitted in the form of optical signals. When it has optical signals applied to it, a transducer constructed as a receiver converts these signals into corresponding electric signals which can be tapped on the output side. The region of a transducer in which the above-described signal conversions are performed is also denoted below as an optically active zone.
The invention relates to an electrooptic arrangement having at least two electrooptic transducers with in each case one optically active zone, having optical connections which are assigned to the transducers and are adjacent at a spacing, and having a coupling device via which optical coupling paths run between the optical connections and the respectively assigned optically active zones.
Such an arrangement disclosed in DE 196 01 955 A1 has a multiplicity of electrooptic transducers (transmitters), each having an optically active zone. When driven electrically in an appropriate fashion, the optically active zones emit radiation which passes via a coupling device into terminals or terminal coupling surfaces of individual optical conductors which are individually assigned to the transducers. The optical conductor ends are arranged adjacently parallel to one another at a regular spacing (increment). The optically active zones and individual lenses constructed on the coupling device on the optical conductor side are constructed at the same spacing or increment. The radiation emitted by the optically active zones passes in this case along coupling paths, which run parallel at a constant spacing through the coupling device, into the optical conductor terminal respectively assigned.
In optical data transmission engineering, there is an increasing need to implement ever higher transmission capacities in an ever smaller space and at costs which are as low as possible. This holds, in particular, for multichannel electrooptic arrangements to which a plurality of optical conductors or other coupling partners are to be connected in each case. The connections are in this case to exhibit a comparatively low spacing from one another (also denoted as pitch or increment). Consequently, the optical coupling paths must also move closer together so that in accordance with the prior design principles the optically active zones of the transducers would also need to be arranged more tightly next to one another. However, this gives rise more sharply to problems of optical and/or electric crosstalk, to a higher outlay on adjustment and to an expensive component miniaturization. The problem of mutual channel influencing (crosstalk) is particularly grave in the case of receiver/transmitter modules (transceivers) with transmitting and receiving channels situated tightly next to one another, because the differences in electric level between transmitting and receiving channels are frequently several orders of magnitude.
It is therefore the object of the invention to create an electrooptic arrangement which, while avoiding an impermissibly high optical and/or electric crosstalk, permits a very tight arrangement of a plurality of optical connections without a high outlay on adjustment and expensive component miniaturization, and thus does so cost-effectively.
According to the invention, this object is achieved in the case of an arrangement of the type mentioned at the beginning by virtue of the fact that the coupling paths run in such a way that the spacing between two optically active zones is greater than the spacing between the assigned optical connections.
An important advantage of the invention consists in that the beams coming along the optical coupling paths from the optical connections and/or passing to the connections are further removed from one another at the transducer end than is prescribed by the spacing (pitch) of the assigned connections. This sharply reduces the sensitivity with respect to electric interference, for example in the case of subsequent electric processing at the receiver end. As a result, there is a relatively large mounting space available on the transducer side independently of the increment of the optical connections, and this has an advantageous effect with regard to the transducer adjustment and the transducer dimensioning.
An advantageous refinement of the invention which manages without mirror surfaces on the coupling device, and thereby has a particularly simple design and reduced transmission losses provides that the coupling device in each case has a boundary with an optically denser medium, which in each case faces an optical connection and is aligned in such a way that the spacings of the coupling paths between the connections and the assigned optically active zones are enlarged toward the optically active zones.
A particularly strong deflection of the coupling paths, and thus a particularly wide spacing of the coupling paths on the transducer side can be achieved according to an advantageous development of the invention in a very small space by virtue of the fact that the coupling device has at least one mirror surface via which at least one coupling path runs between a connection and the assigned optically active zone in such a way that the spacings of the coupling paths between the connections and the assigned optically active zones are enlarged toward the zones.
With regard to the formation and guidance of the beams, further preferred refinements of the invention provide that at least one lens of the coupling device faces the connections, or that at least one lens of the coupling device faces the respective optically active zone,
According to an advantageous development of the invention, the mounting space available for arranging the transducers can be utilized particularly well by virtue of the fact that the coupling device spreads the coupling paths apart in a plurality of dimensions on the transducer side.
It is preferred in terms of production engineering if the coupling device is constructed in one piece. It is particularly preferred that electrooptic transducers and the coupling device can form a single-piece subassembly.
According to a further preferred development of the invention, a particularly simple refinement of the optical connections which can be adapted simply and as required to appropriate standards is possible by virtue of the fact that the connections are part of an optical plug-in device which is constructed for connecting a plurality of optical conductors of an optical conductor plug-in connector.
With regard to the implementation of transceivers described at the beginning, a further preferred refinement of the invention provides that the arrangement comprises a transducer constructed as an optical transmitter and a transducer constructed as an optical receiver, and in that the transducers are arranged on two separate circuit carriers. The arrangement of the transmitter and the receiver on separate circuit carriers is advantageous, in particular, with regard to the outlined crosstalk effects, the production engineering and mounting engineering and the test possibilities.
According to a further advantageous development of the invention, particularly narrow designs are possible by virtue of the fact that the separate circuit carriers are arranged in the direction of the optical conductor longitudinal axes and perpendicular to the mounting plane of the arrangement.
A further refinement of the invention, which is preferred with regard to the transducer arrangement and the use of transducers with vertically emitting (for example so-called VCSEL) or receiving optically active zones provides that the coupling device directs the coupling paths away from one another in opposite directions by 90xc2x0 in each case.
The invention is explained in more detail below with the aid of a plurality of exemplary embodiments; in the drawing: